1. Field of the Invention
This invention relates to apparatus and a method for producing nuclear images of an object under examination. More particularly, this invention relates to nuclear imaging by means of a scintillation camera. Still more particularly, this invention relates to a whole-body scanning apparatus and a method for obtaining nuclear images from a patient.
2. Description of the Prior Art
Scintillation cameras such as the Anger gamma camera (U.S. Pat. No. 3,011,057) are in wide use for producing nuclear images of a patient under examination. Of particular interest are whole-body images of the patient. Whole-body imaging using gamma cameras is performed either by a linear scanning movement of the camera along the patient table, or by a linear scanning movement of the patient table whereby the camera is kept stationary (see brochure "Whole-body Accessory, Models 3222, 3, 4, 5" by Siemens Corporation, Iselin, N.J.; see book "Nuclear Medicine, Technology and Technques", published by the C. V. Mosby Co., St. Louis, Toronto, London (1981), pp. 389-397; see brochure C46A "Pho/Gamma Rota, Introductory Data" by Siemens Gammasonics, Inc.) Scanning is performed in one or more passes.
For data acquisition and imaging a rectangular field of view is produced by masking the camera's field of view either electronically or mechanically. This is done in order to keep the sensitivity of the imaging apparatus constant throughout the scanned area. There are three major disadvantages using this linear scanning technique:
1. There is a trade-off between the scan width of the scanning field of view and the sensitivity of the apparatus. With the scan width chosen large, the scanning field of view has to be small and the scanning speed has to be slow in order to intergrate a number of radiation counts which is sufficiently large for generating a sharp image. With the selection of a wide scanning field of view, or a high scanning speed, the scan width has to be made small. PA0 2. When multiple passes are required to produce the image of the object under examination, faint longitudinal lines appear on the image. These "zipper lines" are generated at the border between the areas covered by adjacent passes. A "zipper line" is due to a slight separation or gap between the areas covered by each pass. Alternately, there may be slight overlaps. The "zipper lines" are irritating in the evaluation of the images. PA0 3. Usually there are high mechanical and installation costs as well as large space requirements.
Electronical rotation of x and y voltage coordinates in nuclear medicine imaging is disclosed in Phys. Med. Biol., 1977, vol. 22, no. 6, pp. 1202-1206, in particular in FIG. 1 on p. 1203.